Vector Network Analyzer for Medical Imaging Research

我们的研究重点是使用射频和微波技术的新医学诊断模式。为了支持这项研究，我们请求资助频率范围高达40 GHz的矢量网络分析仪（VNA）。它提供高频器件和电路散射参数的扫频测量以及两个附加功能：频率转换测量和时域测量。所要求的仪器将取代目前故障和过时的两个vna。旧vna的问题导致实验工作中断，这对我们学员的进步和研究项目的成功至关重要。有三个研究项目严重依赖于所要求的仪器。首先，我们正处于开发用于乳腺癌筛查的微波成像原型的后期阶段。它将为乳房x光检查提供一种急需的非电离替代方法，具有同等或更好的诊断准确性、更广泛的可及性、更低的成本、更高的检查频率和更高的患者安全性。它的模块已经在乳房组织模型上进行了测试，准备在病人身上进行试验，但这些测试现在被搁置了。这还包括开发一种新的超宽带（UWB）接收器芯片，该芯片将集成在乳房成像传感器阵列的每个天线中。该芯片预计将于2022年推出，其特性将需要使用VNA进行频率转换测量。其次，我们正在为7T磁共振成像（MRI）扫描仪和体内核磁共振（NMR）光谱学设计新颖的线圈。7T MR光谱将显著提高脑及周围神经肿瘤、癫痫、多发性硬化症等神经退行性疾病的诊断准确率。MRI线圈测试需要用VNA测量线圈调谐，并验证线圈阻抗匹配和耦合。我们还研究了电子自旋共振（ESR）光谱的生物医学应用，这需要在x波段（10 GHz, 0.33 T）和q波段（35 GHz, 1.25 T）进行测量。第三，我们致力于开发新的辐射计，以克服当前线性度差和精度有限的限制。医用辐射计因其被动性质而具有吸引力——它们不照射病人；它们只能感知人体的自然热辐射。它们用于在热疗和热消融治疗期间监测深部体温。高灵敏度辐射计用于新兴的组织热成像检测恶性肿瘤。基于实验的研究对于通过上述项目实现高影响力创新至关重要。它不仅需要开发具有新功能的硬件，而且还需要支持开发图像重建和处理、异常检测和利用机器学习的自动诊断的新方法。

Our research focuses on new medical diagnostic modalities using RF and microwave technologies. In support of this research, we request funding for a vector network analyzer (VNA) with a frequency range up to 40 GHz. It provides frequency-sweep measurements of the scattering parameters of high-frequency devices and circuits along with two additional functionalities: frequency-conversion measurements and time-domain measurements. The requested instrument will replace two VNAs that are now malfunctioning and obsolete. The problems with our old VNAs brought to a halt experimental work, which is critical to the progress of our trainees and the success of our research projects.    There are three research programs that depend critically on the requested instrument. First, we are in the advanced stages of developing a microwave-imaging prototype for breast-cancer screening. It will provide a much needed non-ionizing alternative to mammography with equivalent or better diagnostic accuracy, wider accessibility, reduced cost, increased check-up frequency, and improved patient safety. Its modules have been undergoing tests with breast-tissue phantoms in preparation for trials with patients but these tests are now on hold. This also includes the development of a new ultra-wideband (UWB) receiver chip, to be integrated within each antenna in the breast-imaging sensor array. The chip tape-out is expected in 2022 and its characterization will require frequency-conversion measurements with a VNA.    Second, we are working on novel coil designs for a 7T magnetic resonance imaging (MRI) scanner and in vivo nuclear magnetic resonance (NMR) spectroscopy. 7T MR spectroscopy will significantly enhance the diagnostic accuracy for brain and peripheral nerve tumors, epilepsy, multiple sclerosis and other neurodegenerative diseases. MRI coil testing requires measurements with a VNA for coil tuning and to validate the coil impedance match and coupling. We also pursue the biomedical applications of electron spin resonance (ESR) spectroscopy, which requires measurements at the X-band (10 GHz, 0.33 T) and the Q-band (35 GHz, 1.25 T).    Third, we work on new radiometers to overcome the current limitations of poor linearity and limited accuracy. Medical radiometers are attractive due to their passive nature - they do not irradiate the patient; they only sense the natural thermal radiation from the body. They are used to monitor the deep-body temperature during hyperthermia and thermal-ablation therapies. High-sensitivity radiometers are used in the emerging thermographic imaging of tissue for the detection of malignancies.    Experiment-based research is critical in achieving high-impact innovation through the projects described above. It is needed not only for the development of hardware with new functionalities but also to support the development of new methods for image reconstruction and processing, anomaly detection, and automated diagnostics exploiting machine learning.